Cells of the atrial myocardium in mammals such as rat, dog, cat and human contain numerous membrane-bound storage granules, and resemble those which are in peptide-hormonal producing cells. Various atrial natriuretic peptides having amino acid sequences in the range of from about 19 to 59 amino acid sequences have recently been discovered.
Thus, DeBold et al., Fed. Proc. 42(3), Abstract 1870, page 611 (1983), report the purification of an atrial natriuretic peptide having a molecular weight of 5150 daltons and a sequence of 47 amino acids, which the investigators designated "Cardionatrin I".
Grammer et al., Biochem. Biophys. Res. Commun. 116(2), 696-703 (1983) discloses the partial purification of a rat atrial natriuretic factor having a molecular weight of approximately 3800 and containing 36 amino acid residues.
Flynn et al., Biochem Biophys Res. Commun. 117(3), 859-65 (1983), and Kangawa and Matsuo, Ibid., 118(1), 131-39 (1984), disclose atrial natriuretic peptides of the rat and human, respectively, having sequences of 28 amino acids.
Thibault et al., FEBS Letters 167, 352-56 (1984) disclose the purification of an intermediate molecular weight atrial natriuretic peptide having 73 amino acids, and Kangawa et al., Biochem Biophys. Res. Commun. 119(3), 933-40 (1984), disclose the purification of an intermediate molecular weight beta-rat atrial natriuretic peptide having 48 amino acids.
Tang et al., Regulatory Peptides, 9, pp. 53-59 (1984) describe five peptides, four of which were isolated from rat atria and the fifth from human atria. These peptides were found to possess natriuretic and diuretic activities and to relax vascular and non-vascular smooth muscles. The four peptides isolated from rat atria were named atrial natriuretic factor and atriopeptin I-III, respectively. The fifth, isolated from human atria, was named .alpha.-human atrial natriuretic polypeptide (.alpha.-hANP). The five peptides contained from 21 to 28 amino acid residues
U.S. Pat. Nos. 4,508,712 (issued Apr. 2, 1985) and 4,496,544 (issued Jan. 29, 1985), inventor Needleman, disclose certain atrial peptides said to have natriuretic activity, with peptides disclosed in the former patent having a high molecular weight and those in the later patent having been obtained by fractionation of rat atrial extracts.